Standard Classification for Rating Outdoor-Indoor Sound Attenuation

Importancia y uso:

4.1 This classification provides a single number rating for transmission loss or noise reduction data that have been measured or calculated. This rating is based on the difference between the overall A-weighted sound level of the sound spectrum given in Table 1 and the overall A-weighted sound level of the spectrum that results from arithmetically subtracting the transmission loss or noise reduction data from this spectrum. The spectrum shape is an average of three spectra from transportation sources (aircraft takeoff, road traffic, and diesel locomotive). A study showed that this classification correlated well with the A-weighted and loudness reductions (based on ISO 532:1975 in effect at the time) calculated for each of the individual spectra used in developing the rating for the one-third-octave band range of 50 Hz to 5000 Hz. The calculated numeric value of the rating is based on the sound transmission loss or noise reduction values for a particular specimen and depends only on that data and the shape of the reference source spectrum used in the calculation. The values shown in Table 1 have an arbitrary reference level. Use single-number ratings with caution. Specimens having the same rating can result in different indoor spectra depending on the variation of their transmission loss with frequency. Also, if the actual spectrum of the outdoor sound is different from that assumed in Table 1, the overall A-weighted outdoor-indoor noise reduction can be different from the OINIC. The strong low-frequency content of the spectrum in Table 1 means that specimen achieving a high rating must have strong low-frequency transmission loss. Use of this classification with the spectrum in Table 1 in situations where the source does not have a spectrum similar to Table 1 could result in requirements for more low-frequency transmission loss than is necessary for the application. Examples where this can occur are stage 3 jet aircraft, high-speed freeways with sound dominated by tire noise, emergency vehicle sirens, and train passes with sound dominated by horns.6

4.2 This classification requires data in one-third octave bands from 80 to 4000 Hz of sound transmission loss (TL) for outdoor-indoor transmission class (OITC), outdoor-indoor noise reduction (OINR(θ)) for outdoor-indoor noise isolation class (OINIC(θ)), or other data based on the rating definition for other ratings based on this classification.

4.3 Due to accuracy limitations given in Test Method E90 and Guide E966 (related to the volume of enclosed measurement spaces), measurements below the 100 Hz one-third-octave band were not reported prior to the development of this classification. Studies have shown that data in the 80 Hz one-third octave band are necessary to obtain acceptable correlations for transportation sound sources. Test Method E90 (when testing façade elements or exterior doors or windows) and Guide E966 now require the reporting of data in the 80 Hz one-third-octave band. For the purposes of this classification, such data are deemed to be of acceptable accuracy.

4.4 The low frequency measurements of sound transmission loss can be affected by the test specimen size or the specimen edge restraints, or both, particularly for small modular specimens such as doors or windows. Consequently, the outdoor-indoor transmission class (OITC) can also be affected by these factors, resulting in some uncertainty of the field performance of assemblies bearing a rating number using this classification, but to what extent is unknown.

Subcomité:

E33.03

Referida por:

E0413-22, C1172-24, E1425-14R23, E0090-23, C0634-22, E0966-18A

Volúmen:

04.06

Número ICS:

13.040.01 (Air quality in general)

Palabras clave:

A-weighting; aircraft; buildings; classification; facade; freeway; indoor; loudness; noise; outdoor-indoor noise isolation class (OINIC(θ)); outdoor-indoor transmission class (OITC); outdoor; railroad; sound; traffic; transmission; transportation;